4gpu 280x = 69Mhs = about 7000AID x 0.00000086 = 0.00602 BTC/daily
(power consumption 870W/h)
0,00602BTC = 2,35$/daily
electricity = 1,12$/daily
2,35$ - 1,12$ = 1,23$/daily
That's good! You pay very little for your electricity...
I pay a lot more so it's no longer profitable for me for a long time now.